Mobile handsets are in widespread use around the world today. One of the most common type of mobile handset is use today is the cellular telephone. Unlike handsets in the past, modern advanced handsets such as the latest cellular telephones incorporate multiple subsystems. In addition to the main cellular radio, handsets nowadays incorporate any number of additional subsystems. Examples include GPS receivers, FM radios, Bluetooth radios, Wireless Local Area Network (WLAN) modems, WiMax modems, Ultra Wideband (UWB) modems, telephone receivers, etc.
A simplified block diagram illustrating several major blocks of an example prior art mobile handset device is shown in FIG. 1. The mobile handset, generally referenced 10, comprises several technology blocks including a WLAN block 12, cellular modem block 14, handset host (OMAP) block 16, UWB block 24, WiMax block 26 and the TX power amplifier block 22, display backlight 18 and antenna 22.
Each of these subsystems, including the basic cellular radio, has different current consumption profiles whereby some have relatively short high peak current demands. Most of the subsystems, however, operate in bursts wherein they consume large amounts of current for short periods of time. Examples of several subsystems that have high peak current demands include WLAN consuming over 200 mA during transmission; the handset display backlight which consumes over 200 mA when active; the cellular radio which also consumes over 200 mA when actively transmitting; the handset host (i.e. OMAP). In addition, UWB and WiMax also exhibit high peak current demand.
By default, the various subsystems are not synchronized with each other. Hence, the peak current consumptions of multiple subsystems will overlap and combine together. This causes the total peak current consumption to increase markedly for possibly long periods of time. Standard prior art handset design are only able to handle overlapping peak currents of the various subsystems that, when summed together, are less than the total peak current the battery and power supply circuit of the handset can handle. For example, the total peak current demand for a complex handset may exceed as much as 1 A.
To meet the total peak current demand of overlapping high current subsystems, larger and more expensive batteries are required along with an increase in the complexity of the design of the power module that supplies power to the entire handset.
There is thus a need for a mechanism that is capable of managing the total peak current demands of the various subsystems in the mobile handset. The mechanism should be able to regulate and limit the total peak current demand of all subsystems such that it does not exceed the current handling capabilities of the battery and power module circuits.